# place default parameters after the non-default parameters
def greet(name, message='Hi'): # define with default parameters
    """ Display a greeting to users """
    return f'{message} {name}'

def sum(n):
    if n == 0:
        return 0
    return n + sum(n - 1)

greeting = greet('smith', message='Hello') # call with keyword arguments
print(greeting)

def get_net_price(price, discount):
    return price * (1 - discount)

net_price = get_net_price(price=100, discount=0.1)

# once use a keyword argument, use keyword arguments for the remaining parameters.

print(sum(100))